CA2262954A1

CA2262954A1 - Burner nozzle

Info

Publication number: CA2262954A1
Application number: CA002262954A
Authority: CA
Inventors: Richard Maricic; Thomas F. Hutchinson, Jr.
Original assignee: Beckett Gas Inc
Current assignee: Beckett Thermal Solutions
Priority date: 1998-02-24
Filing date: 1999-02-24
Publication date: 1999-08-24
Also published as: US6190163B1

Abstract

A burner nozzle includes a burner tube that extends along a central axis and has an inlet end portion for receiving combustible gas and air. At least one body or chamber has a passageway in communication with the burner tube along the central axis which leads to an elongated outlet end portion.
At least one flame-shaping opening is located adjacent the outlet end portion. Each flame-shaping opening may be constructed and arranged effective to elongate (broaden the width of) flame resulting from combustion of the mixture transverse to the central axis to produce efficient heat transfer between the flame and air inside a heat-receiving member disposed downstream of the outlet opening. A flame length reducing member may be used instead of or in addition to the flame-shaping opening and the flame shaping opening may itself reduce flame length. A burner assembly may include a combustion tube in which the burner nozzle is disposed and connected. The burner nozzle is used in a method for broadening and shaping the flame.

Description

FEB 24 ' 99 82: 44Ph1 41RTTS, HOFFhIRPJ3~FISHER
' 14-646 HTJR118a >tiOZZLE
Field of Inven ion:
This invention relates to burners and, more specifically, to gas burners suitable for use in appliances and the like.
Backg~ eund cf t a In e~ noon:
Burners are used, for example, in~apparatuses including furnaces and appliances ouch as clothes dxyers. A principle component of burners is a nozzles typically in the form of a venturi tube. Combustible gas iss fed into this nozzle and 7.0 entrains air into the nozzle. The air and gas is mixed in the vsatur~. cad the mixture emexgea from the outlet end. An ignitor may be attached directly to the venturi tube in front of the outlet opening in alignment with a longii~udinal axirs along which the nozzle extends and ignites the mixture as it leaves the cutlet) thereby ax~eating flame which product~s heat that is utiliaad by the apparatus.
In furnaces, a plurality of burner nozzles are typically arranged side~by-side and are designed for cross-ignition of the gas in adjacent nozzles. one conventional nozzle her two plenum chambers located at an outlet end of the venturi tube.
Each plenum chamber has a thin outlet slit along its side edges. Flame released from the side outlet slits of one nozzle ignites gas from an adjacent nozzle.
Clothes dryer burners may be horizontally fired into dusts of the dryer. The ducts shield the open flame and farce the heated gases in the desired direction. The burner may include an attachment known as a flame spreader which is separately formed from the nozzle, mounted such as by welding to the nozzle and axially spaced from the outlet opening of FEB 24 '99 O~:aSPP4 W~TTS~HOFFMRN~FISHER P.3 the nozzle. Flame spreaders shorten and spread out the flame transverse to a direction of gas flow. xhe flame spreaders are disposed in the flame and thus, are exposed tv relatively high temperatures. This requires the flame spreaders to be fabricated from metals which can Withstand this high temperature environment.
Conventional gas dryer burner noazles typically produce flame having a length of, for example, about one foot.
However, space is limited in the dryer. Long flame lengths to may result in inefficient heat transfer between the flame and air inside the ductwork, overheating of the ductwork, or an increase in the cost of the dryer due to the use of enough ductwork and other components to accommodate the long flame.
Heated gases from the harizantal flame are typically directed through a 90° e?bow, generally vertically to another 90°
elbow, through a scrsen and then into a rotatable drum in which clothes are dried. An air blower may by disposed upstream yr downstream of the burner for directing air in the drum of the dryer.
2o Typical gas dryer burner nozzles can be difficult and relatively expensive to manufacture. Generally) such burner no2zles are fabricated by a practice of shaping the body from tubing and attaching flame spreaders and brackets by welding.
Rnother problem with conventional dryer burner applications is that they are susceptible to igniter breakage. More specifically, the igniters are connected directly to the burner nozzle and, being fragile, may crack or break off during shipping and handling.
summary of the Invention:
The present invention is directed to a burner nozzle for producing shaped and/or shortened flame for efficient heat transfer. The burner is charaCtexiasd by flame-shaping openings for shaping the flame. Rlternativsly, or in combination with the flame-shaping openings, the burner nozals may include a flame lQngth reducing member. The burner is particularly well suited for use in olathes dryers where flame FEB 24 '99 82:45PM bIRTTS~HOFFMRN&FISHEP P.4 that is elongated trangverso to the direction of qas flow and has a reduced length, reduces fabrication costs and results in efficient heat transfer.
=n general, a first embodiment of the invention is a burner nozzle that includes a burner tube that extends along a central axis and has an inlet end portion for receiving combustible gas and air and an outlet opening for releasing a mixture of the gas and air. A main gas flow passage extends along the central axis between the inlet end portian and the 1o outlet opening. At 1~ast one chamber has at lsast a portion disposed alongside and in communication with the main gas flow passage along the central axis. At least one flame-shaping opening is located adjacent the end face. Eaeh chamber extends along the central axis to an associated flame-shaping opening. Each flame-shaping opening is constructed and arranged effective to elongate flame resulting from aombugtion of the mixture transverse to the central axis to produce efficient heat transfer between the flame and air inside a heat-receiving member such as a duct, located downstream of zo the outlet opening.
Ar$ to the specific features of the burner nozzle of the first embodiment, the outlet opening may be disposed along a plane of an end face of the burner tube. Each elongateed flame-shaping opening may be locatad only in or generally parallel to the plane of the end face such that the mixture only leaves the burner tube through each flame-shaping opening and the outlet apenil~g. Each chamber may extend along the central axis to an aesaociated f lame-shaping opening and has a generally uniform height along its entire length. A device for igniting the mixture may be fastened to the combustion tube and positioned offset from the outlet opening and aligned with a flame-shaping opening. The outlet opening ins generally circular and two flame-shaping openings may have a rectangular shape and be located around the outlet opening diametrically opposred from each other.
In general, a second embodiment a~f the ilwention is directed to a burner noaale comprising a burner tube that FEb' 24 ' S9 82: 46Ph1 WF~TTS. HOFF'hlANa~FISHER
' extends along a central axis and hays an inlet end for receiving s combustible mixture of gas and air. A body has a passageway in communication with the burner tube and hoe an elongated outlet and portion. At least one flame shaping opening is disposed ner~x the outlet end portion for releasing a mixture of the gas and air. A baffle formed integrally with the body may project outwardly near the outlet end portion far obstructing air flowing externally of the burner nozzle.
More specific features ~.nclude at least one tab portion that extQnds at an angle with respect to they central axis to obstruct at least a portion of the flame-shaping Qpening.
Each tab portion has a first seotion that extends from the body at an angle with respect to the central axis and a second section that extends from the first section substantially perpendicular to the oentral axis. Also included are a first get of the tab portions and a second set of the tab portions that face eaoh other. The tab portions in the first and second seta extend from the body in an alternating "zipper likap arrangement relative to each other. Alternatively, an arid face may be disposed near the outlet end portion and have at least one angled or curved surface relative to the oentral axis, a plurality cf the flame shaping openings being disposed in the surface. At least one recess rnay project inwardly from the body and restricts the passageway for directing flow of the gas and air in the body.
A preferred aspect of the burnex noazle comprises a burner tube that extends along the central axis and has an inlet end for receiving a combustible mixture of gas and air.
The body has a passageway in communication with the burner 'tube and an elongated out~,et end portion. The end face is disposed near the outlet end portion and has at least one angled or curved surface. A plurality of flame shaping openings are disposed in the surface fox releasing a mixture of the gas and air.
Another preferred a:~pect of the burner nozzle comprises a burner tube that extends along the central axis and hoe an inlet end far reoeiving a combustible mixture of gas and air.

FEF?4 '99 02:4EPM W~TTS.HOFFMAM&FISHER
P.6 The body has a passageway in communisation with the burner tube and an elongated outlet end portion. At least one Blame shaping opening is disposed near the end portion for releasing a mixture of the gas and air. At least one tab portion extends at an angle with respect to the central axis so as to obstruct at least a partion of the at least one flame shaping opening. The tab portion preferably extends outward from the outlet end portion of the burner in a region in which there is no flame or in an initial or cool portion of the dame.
A burner assembly may be formed by fastening the inventive burner nozzle in the interior o~ a combustion tube.
The combustion tube may be comprised of two articles formed of stamped metal or a single rolled form. Wing members flank the burner tube) each wing member being fastened between the articles. Only a single burner nozzle is preferably used in the nozzle assembly, such as in the case of the clothes dryer application. The heat-receiving member or duct comprises a passageway having a portion of a shape that corresponds to the elongated shape of the flame.
A Beneral method of producing shaped f lame from a burner nozzle comprises directing combustible gas and air into the inlet end portion of the buxner tube that extends along the central axis. The gas and air are mixed in the burner tube.
The mixture is directed along the central axis toward an elongated outlet end partion of th~ burner. The mixture is passed through at least one flame shaping opening disposed near the outlet end portion. The mixture is ignited to produce flame. The Blame is shaped to have at least one elongated side portion extending trahsVerse to the central axis.
=n particular, the method may include the following variations. Heat may be directed from the shaped flame to a heat-receiving member located downstream at the outlet opening effective to produce an efficient heat transfer between the flame and air inside the heat receiving member. The heat may be directed from the shaped flame into a passage of the heat-receiving member which hag an elongated portion of a shape FEB 24 ' 99 02: 4?PM I:J~TT~, HOFFM~~&F'ISHER p. ;
' that corr~asponds to the elongated portion of the shaped flame.
A length of the flame may be reduced by diverting the mixture while urfgnited, with at least one diverter portion extending at err angle or direction sa as to obstruct a portion of the at least one flame shaping opening. Flame may be prevented from crass-igniting combustible gas from other burner assemblies.
Air may be obstructed from flowing externally of the burner, using at least one baffle disposed near the outlet end portion. The outlet end partion may be genera~.ly rectangular, and the method may include passing the mixture through the llama shaping openings along the outlet end portion to elongate the flame transvere~e to the central axis. The burner nozzle may camprige a generally circular outlet opening near the outlet end portion which is flanked by two gønerally rectangular side openings, and the method may comprise passing the mixture through the side openings to elongate- transverse to the central axis- the flame from the circular opening.
The present invention offers nu~aerous advantages over prior gees dryer burners . Each ohs~mber and f lame-shaping opening enables elongation of the flame transverse to the central axis of the burner nozzle. This regulte in a flame that has an ideal shape When used with ductwork having a crorrer~ponding elongated te.g., rectangular) passageway. There is an efficient heat transfer between the elongated flame and the air in the duct since there is less wasted space compared to the use of a circular shaped flatus in a rectangular shaped duet, for example.
Alternativ~eiy, or in addition to the flame-shaping feature, the burner nozzle may produce a shortened flame having a length of, fcr example, about half that of aonventior~al burner nozzles used in clothes dryers. In vertical :firing applications there is a shorter distance between the end of the flame and the gentry to the drum than in horizontal firing applications. Therafare, flame that is too long may overheat the ductwork, the screr~n or the dryer load.
The present invention advantageously utilizes a flame length redueirig ~neraber that is not subjected to the intense heat of FEB 24 ' 99 X12: 4?P!v1 WATT, HOFFP1AN&F15HER p, g the flame, resulting in the t~bility to form this mef~ber of the same or different material as the burner noz2le.
The igniter lnay be connected to the cc~mk~usti4n tub$
rather than tc~ the burner nozzle, which is believed will reduce breakage of the fragile igniter. Moreover, the igniter may be aligned with one of the side chambers fnstead of directly in the path of the primary flame) which is believed will result in less heat on and increased life of the igaite~.
Qther embodiments of the inventicsri tire ebntemplated to provide particular features and st~uotural variantr~ of the basic elements. The specific embodiments refereed to as well as possible variations and the various features and advantages of the invention will b~come better understood from the accompanying drawings together with the detailed description that follows.
brief Desorintion of tl~e Drawinas:
Fig. 1 is a perspective vi.ow of an outlet end portion of a gee burner assembly constructed in acGOrdance with the present indention;
Fig. 2 is a top plan vfeW of a burner nozzle shbwn in Figure 1;
Fig. 3 is a areas-sectional view as seen along the plane represented by line 3-3 in Fig. 2;
Fig. 4 is a front elevational view illustrating a ilatae length reducing member;
l~ig. 5 is a side elevatforial view of the flame length reducing member as shown by the lines designated 5-5 in F~.r~.
4;
Fig. 6 is a perspective view of an outlet end partiori of another embodiment of a gas burner assembly constructed in acaordanca with the present invention;
Fig. 7 is an end view of the burner nozzle of Fig. 6;
Fig. 8 is a front view of the burner nozzle shown in Figure s;
35, fig. 9 is a side elevational view of a flame length reducing member as seen slang the lines 8esignated 9i9 in Fig.

FEFi 24 '99 p2:4~PM WATTSrHOFFMRN~FISHER
8i Fig. 10 is an end view of another embodiment of a gas burner nozsle constructed in accordance with the present invention;
Fig. 11 is a front view Qf the gas burner nozzle shown in Figure Zo; and F~.g. 12 is a side elevational view of the burner nozzle as se~n along the lines designated lz-12 in Fig. 11.
Deitailad bescriution of_Preferred Embodiments:
Referring now to the drawings and to Figures 1-4 in particular, one embodiment of a buxn~r assembly constructed in accordance with the present invention is designated generally by reference numeral 10. An outer combustion tube 12 surrounds an interior region 14 in which a barrier nozzle 16 is disposed. The burner naaale includoa a burner tube 18 that extends along a central axis C and has an inlet end portion 20 for receiving combustible gas and air and an outlet opening 22 for releasing n mixture of the gas and air. The out~.et opening is preferably disposed substantially along a plane of an end face 24 of the burner tube {Figure 2). A main gas flow passageway 26 ~xtenda along the central axis between the inlet end portion and the outlet opening. A heat-receiving member 2$, such as a duct leading tv a drum of a clothes dryer, is disposed downstream of the outlet opening relative to a direction of flow of the mixture. Side vhamb~rs~ 30 each have a portion 32 wh~.ch is disposed alongside and in fluid communication with the main qas flow passage along the Central axis. Flame~shaping openings 34 are each located ad~acmnt the end facE~ 24. Each side chamber 3o extends along the central axi. to an associated flame-shaping opening. Each flama-ahaping opening is aonatructed and arranged effective to elongate flame F~. (Figure 3) resulting from combustion of the mixture-- transverse to the central axis, to produce efficient heat transfer bet~asen the flame and air inside the dust.
A gas supply opening 36 at the inlet end portion of the burner tube is sized so that the burner tuba nay be fitted in FEES c4 ' 99 ~2:.'~BPM WF~TT'~-~. H~:)FFMG~N&FISHER P. 18 a conventional manner to a gaa~ halve. The term "qas~~ is used herein in reference to combusstfble fuel. in gaseous form. It will be appreciated that any suitable gaseous combustible fuel may be used, such as natural gas, propane, butane and other gas mixtures. Air supply openlng5~ 38 are faxmed at the inlQt end portion of the burner tube. These skilled in the art wou~,d appreciate in view of this disclosure that the size of the air supply openings may be adjusted as desired to be fixed upon fabrication or may be variable using a shutter, depending upon the air flow requirements of the particular application.
Act the gas flows by the air supply openings it entrains air into the burner tubm.
Each side chamber extends along the central axis alongside the main passageway in communication with the interior of the burner tuba. ~rhe main passageway preferably has a shape shown in Figures 1 arid z that forms a venturi i»
the well known manner. Deps~nding upon the application, none, one or more ~s3.de chambers 30 may be used. However, it is most preferable from the r~tandpoint of design and performance of 2o the burner noazle) especially in the application of clothes dryers, for two side chambers to be used arid for the chambers to flank the burner tube at the outlet end portion as shown in Figure a: The side chambers are preferably spaced apart from each. other by about 180 degrees. ~aah flame-shaping opening 34 communicates with,a side chamber 30 as best shown fn Figure 1, the flame-shaping opening preferably foaming a terminal portion of the sf.de chamber. Each side chamber preferably has a height which is substantially uniform along its ent~.re length along the central axis (.i.e., along aide portion 3z) to the associated flame-shaping opening'. This results in a pressure inside the aide chamber which is approximat~ly the same as or slightly higher than the pressure inside. the main passageway 26. Each flame-shaping opening has an elongated shape, e.g., the flame has a portion with a gsnexally rectangular cross-sectional shape transverse to the central axis (asp shown in Figuxo 3).

DEB 24 '99 ~c:4BPM WGTTS.HOf-FMGN~FISHER P.11 Each flame-shaping opening is preferably located in the planQ of the outlet end face 24 or substantially parallel thereto. Only one burner is preferably used in appliances such as clothes dryexs and thus, the burner nozzle preferably has no openings on a side 40 of the burner tube or on a side of the ehambexs 30 for cross ignition of other burners.
Wing-shaped members or fins 42 are preferably formed integrally with and flanx the burner tuba. Each wing member may include one of the side chambers. The wing members extend outwardly and are cash trapped between two stamped articles 44, 4b. The wing members may be connected to the combustion tube in any suitable manner such as by sliding the ends of the wing members into slots formed in the combustion tube or by trapping them between two halves of the combustion tube as shown in Figure 1. This avoi.def; the need fox separate brackets to att8ch the burner nozzle to the combustion tube.
An igniter component shown generally at 48 is mounted to the combustion tube such as by fastening a bracket 49 to the combustion tube, and is suspended adjacent the burner nozale.
The igniter generates heat which produces the flame as a result of combustion of the mixture of the combustible fuel and air in the wail known manner. Examples of suitable igniters are Model No. 004 WE04 X0739 by Carborundum and Model Nos. 101 and 271 by Norton. Igniters are aomprisad of fragile ceramic material such as silicon carbide and may break if jarred. Fastening the ignites to the Carnbustion tube is advantageous in that it say reduce breakage of the ignitexe during shipment, handling or installation. Any impact on the burner assembly or on the ignites is believed to be distributed across the body of the combustion tube, which may reduce breakage of the ignites.
The life of an ignites is believed to be reduced if it is exposed to cycles of excessive heating and then cooling over extended periods of time. The ignites is preferably offset from the outlet opening in a direction transverse to the central axis and is aligned with one of the flame-shaping openings. This subjects the ignites to r~duced heats since it F-E~ E4 ' 99 t~?: qgpM WqTTS. HUF'FM~N&F'ISHER F'. 12 is dispbeed in flame corresponding to gas from the fiame-shaping openings 34, instead of in flame and signifioantiy greater heat oorYesponding to gas Pram the outlet opening a2 as is c~nvent.iona~.. The present construction also enables the igniter to be positioned further away from the burner tube and any flame shape influencing member. Thin aliow~C the igniter to be mountesi to the combustion tube which may absorb shock better than When the~igniter is connected to the burner nozzle. In the present invention the igniter may be located a so greater distanoe away from the outlet of the burner nozzle than is conventional, in a positiob that is best suited for improving ignition characteristics. For example, the igniter may be spaced apart from the burner tube or the flame-shaping member by a distance ranging from at least about ~ inch to about ~ inch.
The buri~e~ ~a~sembly nay also co~iprise a flame lenQ°th reduoint~ member 50 which may be in the form of an insert that is rvaeivad by the outlet opening zz or may be integrally gormed with the burner tube. In particular, the flame length z0 reducing member 5o is~ preferably used in conjunction with the aide chambers and flame-shaping openings. Alternatively, the flame length reducing member may be used without the side chambers and flame-shaping openil~gs. However, this would pxoduee a longer, generally circular, unshaped flame compared z5 to when the aide chambers and flame-shaping openings are employed. The flame length reducing member 50 may be integrally formed with the nozzle and haV'e a free end bent and connected to the burner nozzle. The member includes a body portion 5a which obstructs a portion of the outlet opesning z2.
30 Pa9eagetS 54 are disposed through the body portion for receiving tile air/gas mixture. Divertar portions 56 ale disposed, each preferably adjacent one of the passages 54, at an angle relative to a direction of flow of the air/gas mixture to div~rt the flow. ~'he diverter portions may be ~5 formod svpsrately from the body portion or integrally therewith. The flamm length reducing member reduces the length of the flame from the burner assembly. conventional FEB ?4 ' 99 J2 ~ 49Ph1 WG~TTS, HOFr hrqN&F'2SHER P. 13 dryers hav~ a limited horizontal space of about 1 '~ to 2 fe~t, for Nxample, in which to position the burner. Ther~for~e, shortening the flame advantageously tailors the heat transfer to use in alotha~s dryers.
Another flame 1~ngth raduCir~g member ~0 aonstruoted accordf,ng to the present invvntiori for use in horizontal spplications, ie shown in figures 4 and s. The member may be inserted into the outlet opening 2~ o~ the burner tube 18.
The me3hber includes a body portion 62 reavived by the cutlet opening having at least one opening 6~ thex°ein which is preferably centrally looated. The body portion may be integrally formed with the burner nozzle and may by fastened at its free end to the burner nozzle in any suitably fashion.
The body may also by received in a groove 66 formed in an end of the burner tube adjacent the outlet opening. The body would be trapped between the upper and lower halves of the burner. Alternatively, the body may be located in a groove further within the burner nozzle and the end portion of the nozzle may be folded over to keep the body in place. Openings ~8 are located around the main opening 64 and improve the performance of the burner. A diverter portion '~0 extends downwardly from the body portion at an angle with ree~pect to a direction of flow of the mixture. The diverter is preferably in than shape of a scoop a8 shown in Figure 5 for effective prevention c~f flame lifting. The mixture passes through the opening in the body while unignited arid is diverted downwardly by the divertar portion of the body. The flame resulting from cornbuetion of the airjgas mixture leaving the outlet opening is generally in the form of a svmicirole. Referring to Figure 4,,the flame F2 corresponds to the mixture from the lower portion of the outlet opening which is unobetruet~sd by the diverter portion. The flame-shaping openings provide elongated sides B to this semicircle shaped flame.
The burner assembly 10 as shown in Figure 1 is suitable 3s for use with both horizontal and verti.oal flow of the air/g°as mixture. A characteristic of horizontal. firing is that the flame has a tendency to rise. The burner must be designed to i~

F~E~ 24 ' 99 02: S~FM IJATTS, HGnFf9ANR~FISHER F. 14 aaeommodate this charactrrristic. Qther concerns are avoiding flaghbar~k and liftoff. Flashback conoorns are addressed, for example, by constructing the chamber with an angled portion 71 (Fig. 1} .
The severity of flashback and liftoff may vary depending upon factors including the type of oombustiblv fuel that is used, port leading and primary aeration. In vertical arid horizontal firing the ~oombust~,on tube and duct have correapond~.ng shapem (e.gr., both are generally rectangular or oval shaped}. The duct: may also be circular such as in horizontal firing fn which case the side chambers 30 may be omitted or used to elongate the flame with their attendant advantages.
Referring now to figure 6, a burger assembly of another embodiment of the present invention is shown gen~rally at 80 and is suitable for use in horizontal and vertical firing applications. More preferably the burner assembly ie~ used in vertical firing applications. The burner assembly includes a combustion tube 8Z that surrounds ari interior region 8~ in ~0 which a burner noaale generally designated 86 is disposed.
The burner no2zle includes a burner tube 88 that extends along a central axis C. An inlet end portion 90 recvivas combustible gas and air. A gas supply opening soo at the intet and portion of the burner tube is siaed sv that the burner tuba may bo fitted in a convent~onai manner to a gas valve. Air supply openings 102 ar.e farmed at the inlet end.
The e4mbustion tube ins preferably formed of two articles of stamped metal x.04, 106. The burner tube extends along the odntral axis within the combustion tube. Wing shaped members ar fine 109 flank the burner tube, and extend outwardly so as to be trapped between the two stamped articles for mounting the burner tube to the combustion tube as described with r~spect to the burner noaz7.e 16.
A generally cylindrical main flow passageway 95 extends within the burner tubes 88 along the cen~rnl axis. from the inlet end portion of the burner nozzle to a body 94. A series of ports 9~ are disposed near an outlet ~snd portion 93 of the l3 FEB 2~1 '99 BE:S~PP1 WRTTS.HC~FF~IAId~FISHER p.15 ( body far releasing a combustible mixture of the gas and air.
An igniter component ilo is mounted to the combustion tube and suspended adjacent the flame-shaping outlet openings by a distance such ae that shown and described in connection with the first embodiment. A heat-receiving member 98, such as a duct leading to a drum of a alothe~s dryer, is disposed downstream of the flame-shaping openinga~ relative to a diroctfon of flow or the mi5ttux~e.
Turning now to gigs. ~-9, the ohamber or body 94 hag a passageway in communication with tlZe main pa~saageway 96. Tha body is preferably integrally formed with the burner tube, The passageway of the body has a shape (e. g., generally triangular or the like) with th~ width of the chamber increasing in th~a direction of the gas flaw to the elongated outlet end portion 93. A generally circular inwardly projecting dimple 117 is disposed on the chambor r~urface.
More preferably) two dimpless are diametrically disposed on opposing chamber surfaces and are preferably 7.ocated along the central axis C. The dimples gradually taper from the chamber surface to a depressed center paint. It is believed that the dimples balance pressure and flow in the burner. As a result, it is believed that the dimples minimize lifting of the flame as it is dfxected away from th8 burner nozzle by enabling faster.moving gases along centerline C to be slowed to a velocity approximating '~h~at of the gas flowing peripherally outsf,de the dimples.
The burner nozzle includes an end face shown gonarally at 108 near the outlet end portion of the chamber. mh~ end face preferably has two, e.g., planar, surfaces 11~. that aro each at an angle of about 40 degrees from the central axis. An arcuate portion A connects the two surfaces. The series of ports 42 are disposed on one cr both of the surfaoes for releasing the aombustfble mixture of the gas and air. The sixes) arranqement and angle of the openings (i.~a., of the surfaoes 111) may be varied as would be apparent to ane aki.lled in the art in view of this disclosure, for example, they end faoe angle may range from 35 to 45 c3egrQes or it. may FEB 24 '99 ~2:51PM WATTS.HOFFMaN&FISHER P.16 be curved.
A secondary air baffle 1z5 is disposed adjacent to the outlet end portion. Preferably, two of the secondary air baffles 115 are used. The secondary air baffle extends parallel to the end portion in a direction B generally transverse to the central axis. It is believed that the secondary air baffles minimize lifting. In particular, the secondary sir baffles herein and in other embodiments of the invention deflect turbulent air from blowers, which axe located upstream or downstreart of the burner, that is traveling in a direction from the burner nozzle inlet end portion to its cutlet end portion, from interfering with the f lame .
As shown fn Figures 7. the flame-shaping outlet openings are preferably elongated or oval shaped. The nozzle assembly preferably has no openings on the side 107 of the burner for cross ignition of other burners. Only one burner 86 is preferably used in the Clothes dryer application. The flame F3 resulting from a combust~lon of the air and gas mixture is shown in Figures 7-9~. Each row of flame shaping openings provide a separate flame that converges into one Blame downstream of the burner nozzle such that en air pocket may exist along the central axis adjacent ~Ghe exterior end portion as shown in~Fig. 9. The flame is elongated and generally six to ten inches in length to produce efficibnt heat transfer between the flame and air inside the dust.
Figures la-12 show another embodiment of a burner nozzle generally at iZ0 for use in the burner assembly 80 instead of the burner nozzle 86, wherein like reference numerals designate like parts throughout the several views. A chamber or body 122 is, for example, preferably generally triangu~.ar shaped or the like, with the width of the chamber increasing in the direction of the gas flow to an elongated outlet end portion 123. A generally circular inwardly projecting dimp~.e 124 is disposed on the chamber surface. Th~a dimple gradually tapers from the chamber surface to a depres~ced o2ntar point.
More preferably) twv dimplea~ are diametrically disposed on FEB c4 "39 0?:51FM 4JRTTS,HOFFMRN&FISHER
opposing chamber surfaces anQ arv pr~afarabiy located along thQ
central axis. Other shapes, size$ and Gonfiguratians of the dimples will be apparent to those skille$ in the art in view of this disclosure, suoh as triangular shapes or cresoent °moon shapes. Aa in the previous embodiments, the dirnplea decree~e the velocity of gas flow along the central axis.
Extending from the end portion 1,23 are a first row of tabs 114 and a second row of tabs 116. The sizes and angles of extension of the tabs may be varied as would be apparent to one skilled in the art f,n v~,ew of this discloaur~.
Preferably, each tab has a first s~ction S1 that is integral with the body (Fig. 12), which extends at an angle of, far example, 45 degrees, from the central axis, ~1 5~econd section S2 of each tab extends fxom the first section at another angle of, for example, 45 degrees, such that the second section is substantially transverse to the central axis (j. e., parallel to the s~condary baffle 132). The tabs are preferably arranged Sipper-like, suoh that a tab from the first row alternates with a tab from the second row as shaven in Figures 10 and 11. The te~b~x 116 are generally upwardly facing and the tabs lie are g~neraliy downwardly facing as shown ~n the drawing, although ft will be appreciated that the present invention should not bo limit~d to diraction~s ssuch as upward and downward, sinaa the burners may be usced in vertical. firing applications. Between oaoh adjaoent tab 114, 116, serf between outermost tab ends and end of the outlet and portion, are spaoes 1a5. Lifting and flashback may be minimized when a poxt~Lon of the tab r52~ is substtantially parallel) to the flame-shaping opening. Also, a space between the outlet end portion where the mixture first leaves th~ body, and the second tab section ~Sa, ~a selected to keep the tabs in the cool portion of flame or not in flame at all, while avoiding flashback and liftoff. Without the portion S2, there may be flame liftoff. The mixtures leaving the nozzle is diverted by the f~,xst and second rows of tabs and results in a flame F4 that ig reduced in length. Rather than employing tabs, the flame length reduainq member 120 may include diverter portions 1d fEB 24 ' 9G p2: 52Pr1 WATTS. HOFFMAfJ&FISHER P. 18 that have other suitable shapes and extend from the burner nozale at suitable angles relative to tho dira~ation of gas flow, for example, in the range of 4dr50 degrees.
Adjacent to the end face is at least one secondary air baffle 132. The secondary air baffle extends parallel to the end face and is generally transverse to the central axis as in the previous embodiment.
Wing shaped m~mbexs or fins 130 flank the burner tube, and extend outwardly so as to be trapped between the two stamped articles for mounting the burner tube to the combustion tube as described with respect to the burner nozzlQ
16. The nozzle assembly prraferably has no openings on the side 131 of the burner for cross ignition of other burners The flame length reducing members of the present invention, 50, 60, 7.11, 114/115, may be received in the outlet opening of the burner tube as inserts or be integrally formed with the body. However) it will ba appreciated that in all embodiments of the prasel~t invention the flame length reduc~.ng members are not subjected to direct flame or at least are disposed in a location where flame is just forming and thus, are in a relatively cool location. Moreover, flame reducing members 50, 60 and 114/116 may be spaced in a direction of the central axis between the outlet end portion or end face of the burner tube, and the igniter, as long as the flame length reducing members are not subjected to the intense heat of the flame. Although not wanting to be bound by theory, the flame length reducing members are not dirw~etly immersed in flame, although flame may curl around portions of the member near openings in the body portion, and as a result, are exposed to lesser temperatures. This may enable the flame length reducing members to be formed of materials which do not need to withstand a very high temperature environment and may inareasa their life.
Using natural gas at 22,000 Btu/h in a clothes dryer, the member 60 of the burner shown in Figures 4 and 5 had a maximum tempexatura o~ 640 aF. The flame length reducing members may be formed of suitable materials such as aluminized or l9 FEB 2~1 'S9 p2:52PI7 WRTTS.HOFFMRNRFISHER P.19 stainless steels. Tn contrast, iri that environment a maximum temperature of a scoop flarrie spreader, Burner No. 32056 by 8eckett Gas, Ins., made of 430 stainless steel, is expected to be at least 1100~F. Burner nozales of the present invention may alsa~ut.ilize Conventional flame spreaders, although this is loss advantageous.
The flame-shaping openings 34, 92, 1a5, ~langate the flame transverse to the longitudinal direot.ian of the burner tube and produce a substantially anal, rather than circular flame (see Figures 3, 4, 7 and 10). The flame may be elongated on only one sido (as a result og selection of the location or arrarigemant of the hales) but is preferably elongated on both sides as seen from the end view, to produce efficient heat transfer between the flame and the air inside the ductwork of corresponding shape. The flame-shaping openinga~ 3~, 92, 125, may also reduce the length of thQ flame somewhat compared to the use of the outlet opening 22 Without the flame-shaping openings. The combustion tube preferably has an elongated shape which approximates a shape of the a0 adjacent duct of the dryer. Therefore) the shaped and/or shortened flame produces heat which is more uniformly distributed throughout the combu:tion tube and duct and results in efficient boat trt~nsfer between the shaped flame, air inside the duct and, ultimately, air inside the drum.
while not wanting to be bound by theory, it is believed there may be a measurable increase in the heating efficiency of clothes in the drum of the dryer (a reduction in BT~7/water evaporated in the drum), which is attributable to the shaped and/or shortened flame.
Tha following are exemplary dimensions of burner nozzle assemblies of the present invention. Each chamber and flame-shaping opening is at least 1/8 inch in height H in both horizontal and vertical firing app7~ications (see, e.g., Figure 3). The chamber is forged with this minimum height to ava~.d the possibility of clogging due to seepage of lint from the drum. In vertical firing the chamber preferably ranges from about ~ inch to about ~ inch in height H. In horizontal FEB 24 ' 9S ~E: 5.?F~~ WATTS. HnF'Fh1f~N&FISHER
firing the width t~ of each side chamber 30, and Width W of each flame-shaping opening, outward from the outlet opening 22 (see Figure 4), ranges from about ~ inch to about ~. inch and, preferably, is about 3/4 of an inch. In vertical firing, the w9.dth W of each chamber and width of each flame-shaping opening, outward from the outlet opening (see Figure 3), ranges from about s ~ inch to about X ~ inch. The dimensions of the burner nozzles shown in Figs. e-12 may be similar to those described above. In the invention, flame length ~ preferably ranges from about 6-10 inches in a combustion tube of about 12 inches in length. All of the above dimensions are provided only for purpo:ee of illustration and the design cf the burner nozzle may be var.~.ed by orie skilled in the art w~.thout departing fxom the scope of the invention, such as in i5 the case of burners of diffvrnnt ~.a~let and outlet opening areas. The above dimensions of thm burner shown in Figure 1-5 are particularly preferred with regard to an outlet opening of about 1 ~ inches in diameter. increasing this outlet opening siEe may result in a corresponding increase in suitable dimensf,ons af.~Ghe chambers and flame-shaping openings.
The combustion tube may be foamed of galvanized or aluminized steel, for example. The burner noazla may be formed of any suitable materials such as aluminized or stainless steel. The combustion tube is preferably formed of z5 two articles of stamped a~etai, which simplifies and reduces the cost of manufacture. The wing-shaped members are preferably formed integrally with and flank the burner tube.
Each wing member includes one of the chambers. The wing members extend outwardly and are each trapped between the two stamped articles, which provides a simple way for mounting the burner tube to the combustion tube.
The burner may be fabricated item two sheet metal halves or from one single sheot. In the preferred and illustrated embodiment, the two halves of the burner are mirror images of one another. This Pac.ilitates cost-effective fabrication since the dies used to fabricate each sheet metal half are also mirror images of oach other. The first step is to size FEB 24 ' 99 ~t2: ~~~iPf1 bIRTTS. HOFFM!~N&FISHER P. 21 each sheet metal half for the appropriate height and width.
Tha height o! the sheet metal includes such factors a8 tho desired height of the side chamber and main passage as well as the width of the wings. The width of the sheet m$tal includes such faotora as the desired length of the main passageway, side ahambera and~gas supply passes~.
The air supply openings in the inlet end portion are farmed in each sheet metal half. The sheet is then stamped in a die configured to form integral "half sections" each l0 containing the faaatures of the nozzle. The two sheet metal halves are then joined together and form a gas tight seam.
Tn the case of a burner which employs a flame length reducing member, o>ne or both of the sheet metal halves may bs stamped to include the shape of the t~lame length reducing mamber(a). The diverter portions when formed integrally with thr~ body, may be bent to the desired angle. The member may then be bent 90° i>~fto position and fastened in the outlet opening of the burner nozzle. This enables the member to be fabricated oasily in a cost effective manner, since the member 2a need not be separately formed and then attached with melding or the like.
In the case of the flame reducing member 112 shown in gigures 6-9, a single metal sheet may be used to fabricate the entire burner nozzle. A dies is fabricated tc~ stamp onto a single metal sheet an image containing the features of thm flame length reducing melro~bers and burner. The image is comprised of two mirror images Por each halg section and is bent such that the mirror images are superimposed and an arcuate portion may be formed about the axis at which the 3d metal is bent. The planes having the flame-shaping openings contained th~rein are preferably at a 35-45 degree angle from the central axis or tray b~ tapered or curved. The top and bottom halves are avcured such that a tight gas seal exists.
Regarding operation of the burner of the first embodiment, for example, combustible gas is ~ed into the gas opening of the burner tube from the gas valve in a manner known to those skilled in the art. ,fir is entrained by the FEB 2-4 ' 99 t~2:53Pf~ WHTTS. HcJFF;~IafJ~FISHER P. ~~
gas into the burner tube. The air and gas is mixed in the venturi and travels toward the outlet end portion. A portion of the air and gas passes into each side chamber to the associated flame-shaping opening. A principal portion of the air and gas flows through the main passageway to the outlet opening. In the other embodiments, the air and gas inside the burner tube enters the body or chamber 94, 122 and travels thxough the flames-shaping openings 92 or 125.
The ignites is prafarably in alignment with one of the l0 flame-shaping openings 34, s2) 125. The ignites is operated in a known manner arid flames results from oambustion of the air/gas mixture. The flame-shaping openings shape the mixture, resulting in flame having sides elongated transverse to the central axis. Tn the vase of the flame-shaping openings 3~) the circular flame fxom,the autl.at op~ning is elongated by the flame shaped by the dame-shaping op4nings.
When the flame length reducing member is used, the air/gas mixture from the outlet opening is diverted by the diverter por'tiona. Dapanding on the horizontal or vartiaal application, an appropriate burner nozzle with one of the described burner nozzles is selected. The resultant diverted mixture is ignited by the ignites. This produces a f~.ame having a length that may be reduced by about 1T-50~ from a conventional flame length c~f 12 inches and has a generally oval shape. The flame travels through an either vertically or horizontally oriented combustion tube depending upon the application, arid the resultant heated gases are evenly distributed throughout the combustion tube in v~.ew of its corresponding elongated cross-sectional shape. The heated 3o gases travel from the combustion tube into adjacent ductwork, The heated air travels through the ductwork to the drum where it dries clothes rotating in the drum. The burner nozzle of the present invention results in temperatures which avraid overheating of the ductwork. These heat aharaateristias are due to the elongated and/or shortened flam~.
Although the invention has been described iri its preferred form with a certain degree of particularity, it will ~1 FEE =4 '99 ~~:54FM WRTTS,HOFFMRN&FISHER R,~S
be understood that the present disaloeura of preferred embodiments has been made only by Way of example and that various changes may be resorted to without departing from the true spirit arid scope of the invention as hereafter claimed.
as

Claims

1. A burner nozzle for producing shaped flame for efficient heat transfer, comprising:
a burner tube that extends along a central axis and has an inlet end portion for receiving combustible gas and air, an outlet opening for releasing a mixture of said gas and air, said outlet opening being disposed along a plane of an end face of said burner tube and a main gas flow passage extending along the central axis between said inlet end portion and said outlet opening;
at least one chamber at least a portion of which is disposed alongside and in communication with said main gas flow passage along said central axis; and flame-shaping means for elongating on both sides transverse to the central axis flame resulting from combustion of said mixture effective to produce efficient heat transfer between said flame and air inside a heat-receiving member located downstream of said outlet opening.

2. The burner nozzle of claim 1 wherein said flame-shaping means comprises elongated flame-shaping openings flanking said outlet opening and located only in or generally parallel to said plane such that said mixture only leaves said burner tube through each said flame-shaping opening and said outlet opening,

3. The burner nozzle of claim 1 wherein said flame-shaping means comprises elongated flame-shaping openings flanking said outlet opening, each said chamber having a length that extends along the central axis to en associated said flame-shaping opening and having a generally uniform height along its entire length.

4. The burner nozzle of claim 1 wherein said flame-shaping means comprises elongated flame-shaping openings flanking said outlet opening, said outlet opening is generally circular and two of said flame-shaping openings have a generally rectangular shape and are located around said outlet opening diametrically opposed from each other.

5. The burner nozzle of claim 1 comprising a flame length reducing member comprising a body portion that obstructs a portion of said outlet opening and has at least one opening therethrough for receiving said mixture and at leant one diverter portion extending from said body portion at an angle with respect to a direction of flow of said mixture.

6. The burner nozzle of claim 1 wherein said flame-shaping means comprises an elongated flame-shaping opening which forms the outlet opening and has an entirely generally rectangular cross-sectional shape along the end face of the burner tube, further comprising tab portions extending at an angle with respect to a direction of flow of said mixture near the outlet opening.

7. The burner nozzle of claim 6 wherein said flame-shaping opening is located only in or parallel to a plane of said outlet end face of said flame-shaping chamber such that said mixture only leaves said burner tube through said flame-shaping opening.

8. The burner nozzle of Claim 7 wherein the at least one said chamber has a generally uniform height along an entire length of said chamber that extends along said central axis to said flame-shaping opening.

9. A burner nozzle got producing shaped flame for efficient heat transfer, comprising:
a burner tube that extends along a central axis and has an inlet end portion for receiving combustible gas and air, an outlet opening for releasing a mixture of said gas and air, said outlet opening being disposed along a plane of an end face of said burner tube and a main gas flow passage extending along the central axis between said inlet end portion and said outlet opening;
at least one chamber at least a portion of which is disposed alongside and in communication with said main gas flow passage along said central axis; and at least one flame-shaping opening located adjacent said end face, each said chamber having a length extending along the central axis to an associated said flame-shaping opening and having a generally uniform height along its entire length, wherein each said flame-shaping opening is constructed and arranged effective to elongate flame resulting from combustion of said mixture transverse to said central axis to produce efficient heat transfer between said flame and air inside a heat-receiving member located downstream of said outlet opening.

10. The burner nozzle of claim 9 comprising a flame length reducing member comprising a body portion that obstructs a portion of said outlet opening, at least one opening therethrough for receiving said mixture while unignited and at least one diverter portion extending from said body portion at an angle with respect to a direction of flow of said mixture.

11. A burner nozzle for producing flame having a reduced length for efficient heat transfer, comprising:
a burner tube that extends along a central axis and has an inlet end portion for receiving combustible gas and air, an outlet opening for releasing a mixture of said gas and air, said outlet opening being disposed at an end face of said tube and a main gas flow passage extending along the central axis between acid inlet end portion and said outlet opening, and a flame length reducing member comprising a body portion that obstructs a portion of said outlet opening and has at least one opening therethrough for receiving said mixture while unignited and at least one diverter portion extending from said body portion at an angle with respect to a direction of flaw of acid mixture.

12. The burner nozzle of claim 11 further comprising a chamber adjacent to said end faces extending alongside from said central axis and in communication with said main gas flow passage along said central axis for regulating gas flow.

13. A burner assembly for producing shaped flame for efficient heat transfer, comprising:
a combustion tube surrounding an interior region;
a burner nozzle disposed in said interior region and connected to said combustion tube, said burner nozzle comprising a burner tube that extends along a central axis and has an inlet end portion for receiving combustible gas and air, and an outlet opening for releasing a mixture of said gas and air;
at least one chamber adjacent said outlet opening in communication with an interior of said burner tube along said central axis; and at least one flame-shaping opening located adjacent said end face, each said chamber extending along the central axis to an associated said flame-shaping opening, wherein each said flame-shaping opening is constructed and arranged effective, to elongate flame resulting from combustion of said mixture transverse to said central axis to produce efficient heat transfer between said flame and air inside a heat-receiving member disposed downstream of said outlet opening.

14. The burner assembly of claim 13 wherein each said elongated flame-shaping opening is located only in or generally parallel to said plane such that said mixture only leaves said burner tube through each said flame-shaping opening and said outlet opening.

15. The burner assembly of claim 13 comprising a flame length reducing member comprising a body portion that 26~

obstructs a portion of said outlet opening, has at least one opening therethrough for receiving said mixture while unignited and at least one diverter portion extending from said body portion at an angle with respect to a direction of flow of said mixture.

16. The burner assembly of claim 13 wherein said combustion tube is comprised of two articles formed of stamped metal.

17. The burner assembly of claim 16 comprising wing members flanking said burner tube, each said wing member being fastened between said articles.

18. The burner assembly of claim 13 comprising means for igniting said mixture fastened to said combustion tube and aligned with one said flame-shaping opening.

19. The burner assembly of claim 13 wherein paid outlet opening is generally circular, comprising two of said flame-shaping openings having a rectangular shape and located around said outlet opening diametrically opposed from each other.

20. The burner assembly of claim 13 comprising only a single burner nozzle.

21. The burner assembly of claim 13 wherein said heat-receiving member comprises a passageway having a portion of a shape that corresponds to the elongated shape of said flame.

22. The burner assembly o! claim 13 wherein said flame-shaping opening forms the outlet opening and has an entirely generally rectangular arose-sectional shape slang the end face of the burner tube, further comprising tab portions extending at an angle with respect to a direction of flow of said mixture near the outlet opening.

23. A burner nozzle comprising:
a burner tube that extends along a central axis and has an inlet end for receiving a combustible mixture of gas and air, a body having a passageway in communication with said burner tube and having an elongated outlet end portion, at least one flame shaping opening disposed near said outlet end portion for releasing a mixture of said gas and air, and at least one baffle that is integrally formed with said body and extends outwardly from said body near said outlet end portion far obstructing air flowing externally of said burner nozzle.

24. The burner nozzle of claim 23 wherein at least one tab portion extends at an angle with respect to said central axis to obstruct at least a portion of the at least one said flame-shaping opening.

25. The burner nozzle of claim 24 wherein each said tab portion has a first section that extends from said body at an angle with respect to said central axis and a second section that extends from said first section substantially perpendicular to said central axis.

26. The burner nozzle of claim 24 comprising a first sot of said tab portions and a second set of said tab portions that face said first set of said tab portions, wherein said tab portions in said first set and said tab portions in said second set extend from said body in an alternating arrangement relative to each other.

27. The burner nozzle of claim 23 comprising an end face disposed near the outlet end portion and having at least one angled or curved surface relative to said central axis, a plurality of said flame shaping openings being disposed in the at least one said surface.

28 28. The burner nozzle of claim 23 wherein at least one surface projects inwardly from said body and restricts said passageway for directing flow of said gas and said air.

29. A burner nozzle comprising:
a burner tube that extends along a central axis and has an inlet end for receiving a combustible mixture of gas and air, a body having a passageway in communication with said burner tuba and having an elongated outlet end portion, an end face disposed near the outlet end portion and having at least one angled or curved surface, and at least one port disposed in the at least one said angled surface for releasing a mixture of said gas and air.

30. The burner nozzle of claim 29 wherein said end face extends at an angle ranging from about 35 to 45 degrees with respect to said central axis.

31. A burner assembly comprising:
a combustion tube surrounding an interior region;
and a burner nozzle disposed in said interior region and connected to said combustion tube, said burner nozzle comprising:
a burner tube that extends along a central axis and has an inlet end for receiving a combustible mixture of gas and air, a body having a passageway in communication with said burner tube and having an elongated end portion, at least one port disposed near said end portion far releasing a mixture of said gas and air, and an end face disposed near the outlet end portion and having at least one angled or curved surface relative to said central axis, wherein the at least one said part is disposed in the at least one said surface, wherein the at least one said port is constructed and arranged effective to elongate flame resulting from combustion of said mixture transverse to said central axis to produce efficient heat transfer between said flame and air inside a heat-receiving member disposed downstream of said outlet opening.

32. A burner nozzle comprising:
a burner tube that extends along a central axis and has an inlet end for receiving a combustible mixture of gas and air, a body having a passageway in communication with said burner tube and having an elongated outlet end portion, at least one flame shaping opening disposed near said and portion for releasing a mixture of said gas and air, and at least one tab portion extending at an angle with respect to said central axis so as to obstruct at least a portion of the at least one said flame shaping opening.

33. The burner nozzle of claim 32 wherein the at least one said tab portion extends at an angle ranging from about 40 to about 50 degrees relative to the central axis.

34. A burner assembly comprising:
a combustion tube surrounding an interior region;
and a burner nozzle disposed in said interior region and connected to said combustion tube, said burner nozzle comprising:
a burner tube that extends along a central axis and has an inlet end for receiving a combustible mixture of gas and air, a body having a passageway in communication with said burner tube and having an elongated outlet end portion, at least one flame shaping opening disposed near said outlet end portion for releasing a mixture of said gas and air, and at least one tab portion extending at an angle with respect to said central axis so as to obstruct at least a portion of the at least one said flame-shaping opening, wherein the at least one said flame-shaping opening is constructed and arranged effective to elongate flame resulting from combustion of said mixture transverse to said central axis to produce efficient heat transfer between said flame and air inside a heat-receiving member diseased downstream of said outlet opening.

35. A method of producing shaped flame from a burner nozzle, comprising the steps of:
directing combustible gas and air into an inlet end portion of a burner tube that extends along a central axis;
mixing said gas and said air in said burner tube;
directing said mixture along the central axis toward an elongated outlet end portion of said burner;
passing said mixture through at least one flame shaping opening disposed near said outlet end portion;
igniting said mixture to produce flame; and shaping said flame to have at least one elongated side portion extending transverse to the central axis.

36. The method of claim 35 comprising directing heat from said shaped flame to a heat-receiving member located downstream of said outlet opening effective to produce an efficient heat transfer between said flame and air inside said host receiving member.

37. The method of claim 35 comprising directing the heat from said shaped flame into a passage of said heat-receiving member which has an elongated portion of a shape that corresponds to said elongated portion of said shaped flame.

38. The method of claim 35 comprising reducing a length of said flame by diverting said mixture while unignited with at least one diverter portion extending at an angle so as to obstruct a portion of the at least one flame shaping opening.

39. The method of claim 35 comprising preventing flame from cross-igniting combustible gas from other burner assemblies.

40. The method of claim 35 comprising obstructing air flowing externally of the burner using at least one baffle disposed near said outlet end portion.

41. The method of claim 35 wherein said cutlet end portion is generally rectangular, comprising passing said mixture through the at least one said flame shaping opening along said outlet end portion to elongate the flame transverse to said central axis.

42. The method of claim 35 comprising a generally circular cutlet opening near said outlet end portion which is flanked by two generally rectangular aide openings, comprising passing said mixture through said side openings to elongate transverse to said central axis the flame from said circular opening.